Jpn. J. Appl. Phys. 50 (2011) 01BF02 (5 pages)  |Previous Article| |Next Article|  |Table of Contents|
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Improved Optical Degradation Characteristics of Eu Complex Encapsulated by High-Pressure Annealing

Sayaka Kato, Takeshi Fukuda, Shinnosuke Akiyama, Zentaro Honda, Norihiko Kamata, and Naoto Kijima¹

(Received June 25, 2010; accepted August 30, 2010; published online January 20, 2011)

The instability of Eu complexes against ultraviolet (UV) light irradiation is an important problem to solve before they can be practically applied in white light-emitting diodes. A novel technique of encapsulating tris(2-thenoyltrifluoroacetonato)(1,10-phenanthroline)europium(III) [Eu(TTA)₃phen] was investigated using high-pressure annealing (solvothermal process) as a final process in the sol–gel synthesis. The photoluminescence and excitation spectra of encapsulated Eu(TTA)₃phen samples synthesized by solvothermal and conventional annealing processes were almost the same. A half brightness time of 589 min was achieved while irradiating with UV light of 360 nm and 5 mW/cm² by optimization of ammonia concentration and annealing temperature. The longest half brightness time was longer than that of encapsulated Eu(TTA)₃phen synthesized by conventional thermal treatment. One possible reason for this result is that the chemical reaction of the sol–gel based glass network occurs more efficiently with high-pressure annealing. As a result, a high encapsulating efficiency was achieved owing to the small amount of organic component in the sol–gel derived glass network.

URL: http://jjap.jsap.jp/link?JJAP/50/01BF02/
DOI: 10.1143/JJAP.50.01BF02
PACS: 78.20.-e, 78.55.Kz, 61.80.Ba, 81.20.Fw, 81.40.Ef

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